ali p how does he understand it? He just explained it’s ok. He showed no examples or reasoning as to why. Having 20+ years in machine and car shops and understanding tolerances and bearings back pressure under load or not is still pressure. Which is going to put force on the bearings which will wear one direction more than another. This wearing the bearings to premature failure. The whole it wears under WOT but not when it’s no makes no sense. Either way it’s back pressure on the turbine and bearings. So either it does or doesn’t at all.
Dan Slotea not true, they are mainly in place to prevent the noise and due to they fact that many standard hot wire/thin film air flow meters could not measure the direction of air flow, and as surge when surge occurred the air flow meter incorrectly measured more air than was being consumed by the engine, causing a temporarily rich tune and emissions problems. The Anti surge was just a happy coincidence, many early turbo cars of the 80s had no bov.
@@renners9636 Many 80s cars also had Brown interiors, solid rear axles and were absolutely terrible. It doesn't make them correct. Also that was like 37 years ago, technology changes. Look at Borg Warner.
No Grip can you be more specific in your argument against me? My statement was very simple and only covered one aspect, that the main reason cars were initially fitted with blow off valves was not to protect against *damage* from compressor surge itself but to stop incorrect fuel readings under surge conditions and to stop annoying noises that most drivers would not expect from a normal car. I made absolutely no claim of anything being better, the implication of me mentioning some 80s gasoline cars not having blow off valves was to validate the 100s of thousands of turbochargers that have lived and live without being destroyed by compressor surge, I never advocated it as correct, but simply noted in the case of many oem cars that it is was a design that did not doom the turbocharger to early mechanical failure. Manufacturers are more worried about possible emissions and noise issues than a few turbos failing sometime after warranty is up. Maybe turbos running 30+psi are more susceptible to wear I couldn’t say.
maybe 10% its clearly not bov. BUT some of the turbo cars that makes flutter noises does have bov but it only realeases part of the boost so the sound is kinda mixed
This is an automatic message to notify anyone that ErwinSchrodinger's quad turbo charged & dual supercharged Civic Si, with stock internals, had so much horsepower and so fast, it became a time machine and he went back in time.
Been running no BOV on my single turbo 1JZ for near on 3 years now. Makes 20+psi on e85 reliably all day every day without issue. Why fix something if it isn't broken?!
Archer old turbo buicks with blow thru system didnt have bovs and you can still find perfectly working ones with the same old turbo. so after 25+ years and thousands of miles and still no broken turbo...
andrenegwer says the guy parroting what he saw in a video from a very respectable, but less experienced member of the community. They are much more experienced experts who will tell you the opposite. What he covers is is mostly true but you still cause premature wear without a valve regardless.
I get the best of both worlds with the Tial Q on my ms3. Spring in it is a -12 psi spring, and the vacuum in the intake manifold takes about a quarter to a half second to go from positive boost to -12 vacuum, and therefore it takes that long before the valve opens after boost. I get this lovely "stutu-schhhhh" noise from it and I absolutely cannot wait until I have a Garrett GTX2867R gen II on it and can hear the noise a 9 blade compressor makes vs the k04 6 blade.
If you're running the correct sized turbo, intercooler and piping for your setup, a BoV isn't necessary, the only thing a BoV MIGHT, and I stress the might, help with is eliminating lag (if you even have any) between gear changes as the turbine of the turbo won't slow down as much with the surge of pressure when the throttle blade is closed. As for the increased wear on the turbo when not using a BoV, for every study I've seen saying that it wears the turbo quicker, there's another that says it won't! :/ From my own experience, the only benefit I've noticed from a BoV has been reducing lag between gear changes. I put something like 15000 miles on a mk3 Supra 2.8 single turbo I built back in 1999 without a BoV then after some advice from a mk4 Supra owner, I fitted a BoV and it did help to eliminate the lag I was getting between gear changes. I ran the car for 2 years after that (must've been at least another 20000 miles) without any noticable signs of wear on the turbo, I sold the car to a friend who ran it just over a year before smashing it and one of the few things that was ok to salvage was the turbo!
Yeah, hear changes and when you close the throttle before reopening, I have noticed slight differences in lag reduction with a well placed BOV, as for longevity... I don’t think it’s that dramatic of a difference with our without as long as your system in balanced like you said
I'm under the impression you're mistaking the purpose of a blowoff valve and a wastegate. The boost control solenoid in conjunction with the wastegate and recirculation valve is what should maintain boost pressure between shifts, a blow off valve in theory is only there to blow off air pressure when you come off throttle
@@theposerhoser No he's correct. A wastegate is only there to prevent overspeeding of the turbo. A recirculation valve has a very similar job as a bov, a bov vents to atmosphere and a recirculation valve vents back to the inlet of the turbo. Not sure why you added the wastegate to the mix.
Car Throttle THANK YOU!! At fucking last somebody got it right!! Seriously: Utmost respect to you for actually RESEARCHING this subject and not just repeating what every forum / back of BOV box said.
haha love my vl and I was surprised it made it into what I assume is an american made video but almost all turbo vls are bound to be flutter machines. Mines soon to join the turbo charged crew ;)
As a Machinist/Welder/Fabricator/Mechanical Engineer, in 2004 or there about's, I got to work on a diesel semi-tractor that was attempting a Bonneville world speed record for that class. The diesel engine was turbocharged and producing 75+ psi. The turbo stall was discovered with a high-speed camera aimed at the fan. This wheel was coming to near complete stop and re-spooling. The solution was to add a Roots Blower to the mix to positively insure that the flow from the turbo was moving forward. This semi was geared so tall that it needed another tractor to push it to 75 mph just to get going in first gear.
Well, this is the coolest thing I've read all day. Funny enough a day that someone was trying to tell me how bad compressor surge is, which is why TH-cam suggested this video to me. Do you happen to remember who or what company that was? It wasn't Cat with the race C10, was it?
Got a link to a video of that? cause it sounds bullshit to me. Turbos spins at tens of thousands of rpms, it's not going to stall and come anywhere near a complete stop in between gears. That's an outrageous claim
Had my own turbo spin the nut off the compressor due to closed throttle surge and seen others do it too. It is all good if your turbo runs a left hand threaded shaft but the ones i have seen undo are right hand threaded. The turbines inertia due to weight is greater than the compressor wheel so it tends to back off the nut on the compressor wheel when there is a differential of forces applied. Cheers.
Already knew, but it's nice to see someone else who doesn't believe the forum ninjas. For everyone who isn't sure ; Blow off and recirc valves only help stop compressor stall on over run/closed throttle. Usually vacuum operated, though I did see a rather complex electric set up that was supposed to keep it spooling longer. The best way to do that is antilag, but that's the easiest way to shorten the life of any turbo, but so much fun.
Pushing 24psi no bov/dv for atleast 6 months daily driven. No issues yet. It makes sense that the free spinning turbo can chop the air with reverse pressure with minimal wear to the bearings/shaft because of its free spinning state.( whatever exhaust flow from the engine while shifting wouldnt be nearly the pressure returning through the intercooler) I don’t understand why so many others preach its pre detonation of the turbo?
I've had a ghetto blanking plate on my WRX Wagon's stock recirculation valve for over 5 years and 40,000 miles with no issues. If you want flutter then I highly recommend it. Every genuine expert I've spoken to had said it's not going to cause any harm. Especially in a stock turbo that doesn't run particularity high boost. 👍
I think it depends on the tuning set up if a blow off valve is necessary. In my car i had the recirculation factory valve . It makes a chousss sound. Lately there's a problem that causes loss of boost and i have to go to my mechanic to solve it. By the way what is ghetto blanking plate?
I had seen some comments about that and I never did understand how it could spin the compressor backwards, turbochargers are essentially non-postive displacement pumps and a fluid pushed backwards through one would be extremely inefficient at causing any movement of the compressor wheel.
Its scary to me that people don't actually get this as it's the most BASIC understanding of how a turbo works. Think about that for a while. these are the same people that yell ''RICER'' if you made a modification they don't approve of.
It sounds to me like you're just band-wagoning, because you aren't really providing reasoning behind your argument. You're simply persecuting. Compressor surge fundamentals are not the most basic understanding of how a turbo works. That's usually stage 2 or stage 3 in understanding a turbine's mechanics. An inexperienced person who has just finished their build wouldn't likely be aware that their blow-off valve serves purpose outside of alleviating pressure in charge pipes and intercooler piping/intercooler. If they heard open throttle compressor surge for the first time, they might just assume it's cool turbo noises and functioning as normal. Once they've blown the seals and bearings out of the turbo, then it might be something they learn. Also, some of your statements don't even correlate. You're a bit all over the place, which is what leads me to the conclusion that you're simply here to make others feel bad to make yourself feel better about your own ignorance. I'm not attacking you, but I would ask that you not attack others. If you think you have such a complete grasp on turbo-charging, perhaps you should do some research into intake harmonics and then come back and comment. You still have a lot to learn as well. Everyone starts somewhere. Learning is a process. I've spent years of my life building turbo'd cars and still learn things every day through trial and error, other people providing me information and tips, and research and equations. If you assume compressor surge is a fundamental pillar in understanding turbo-chargers, you've never seen a 16 year old driving a boosted Civic with no blow-off valve, no intercooler, no waste-gate, and no BCM or piggy-back. Turbo-charging is more complex than you are for probably prepared.
@@the_modfied_car4903 do you understand how bearings, friction, impact and directional force work? Cause what you said makes me think you don't. Turbo flutter is puts force on the fins in one direction, abruptly ceases that energy, which causes secondary forces to commence. This is a back and forth motion that wears down bearings and shafts. A smoother change in pressure results in less violent motion and reduced wear. You don't know what you're talking about. Fluid dynamics are all fine and dandy in theory but mechanical elements are your point of wear. Anything that moves, wears. You combine the immense heat and rpm a turbo operates at and you get accelerated wear. Not to mention the difference between double-sleeve, sleeve-bearing, and dual-ball-bearing turbos. Turbo flutter causes wear. Arguing against that isn't ignorance now, because you should know better. Arguing against it is stupidity because you're arguing against physics. This kind of wear is demonstrated by the price-hike of dual-ball-bearing turbos despite them being cheaper to manufacture than other varieties. It's because those forces don't wear them AS much, but still do. I just...I can't even talk to you right now. If you don't know something, ask. But don't try to teach people incorrectly.
thanks CT that cleared my confusion. Now I can have highest settings during acceleration with no flutter , but only after you lift the throttle-closed.
I could be wrong but having a bov does make for much quicker boost response if you are going to be on and off the throttle frequently as in road racing,time attack,off road rallying and auto cross.
Thank goodness I had this saved cuz my dad did t believe me when I told him it wasn't bad to not have a blow off valve. This video amongst much more research finally proved to him it wasn't bad for my car which I bought myself that he has never and will never need to put money into
As a father, I will act like that, because it makes my kids want to prove me wrong. It's a kind of test to see what lengths they will go to prove what you think is real. Also you learn more from doing so rather than not having to. Have fun out there in your turbo rig. 🤙
I have a book by career long mechanics that I explained before that goes over this and you do cause premature fatigue failure on turbos and increase turbo lag without a compressor bypass/blow-off valve. With the valve you prevent pressure waves going back into the impeller and the impeller is kept spinning without interruption reducing lag. I’d rather not put any stress on my expensive parts than do so just to hear “wooooooosh Stu-Stu-Stu-Stu-Stu”
I'd say it depends. If you're letting off the throttle for a brief moment (like changing gear) residual pressure that haven't gotten out through the turbo yet will help to build the target pressure faster, but if you let off and leave it for a longer time (so the pressure can completely escape), then yes, rotor will take more time to spool up. Nevertheless, in both cases, the differences are barely noticeable.
Lag is actually the time it takes for the pressurised air from the turbo to make it to the manifold. A top mount will have less lag than a front mount typically.
Ok, the hot side is the turbine, the cold side is the compressor. They spin at the same time being linked with a solid shaft. Ok moving on, what you're probably trying to describe is boost threshold where there is enough exhaust gas to spin the turbo to the point it produces positive pressure. Turbo lag as I said above is what happens above that boost threshold.
The first problem I see with this video is while yes, you're right in your explanation dispelling this myth - but "Oh you're wrong because 'Car Throttle Extra' said so" is most likely not going to cut it. Maybe you could cite your sources behind the logic explained in this video?
There can be surge with wide open throttle as well.... If you mismatch the compressor wheel with the engine flow demand. Its not the air that is trapped. Its the compressors wing stall that makes the fluttering noise. You can also have surge in airplane engines as well and it vibrates in similar fashion.
Never had a turbo issue due to closed throttle surge, both cars for over 5 years now. Good video, easy enough for all keyboard warriors to hopefully understand...
Heads up for those that run a Maf sensor on the turbo inlet, subaru guys I'm talking to you. Doing this mod will cause problems with your tune. The air moving out of the turbos inlet on closed throttle is being metered and telling the computer it needs more fuel to go into the cylinders on closed throttle.
Ran no BOV on 240sx KA-T it felt like a better turbo response not to have a BOV, because when I'm off throttle the would turbo flutter for around 2 second. So I guess for those 2 sec, it's like I have reservoir of boost ready to use. So If I opened the throttle within 2 seconds after closing the throttle the boost would just shoot back up to the boost limit almost instantly.
It can’t surge if it has no load No load no surge Just pretty pretty noises Tbh the only advantage a BOV is in a manual car so the turbo doesn’t slow between shifts.
The only thing a bov does is stop back flow when throttle is closed. To keep the turbo spinning in between shifts you need a recirculating valve that reintroduces the air into the turbo intake
Thanks for addressing facts, there is so much misinformation online it’s unreal, magazines still publish about compressor surge to try and sell turbo smart BOV’s lol, fair enough that if you have higher boost and too much trapped air then extra resistance against the impeller over a longer time frame may not be the best thing, but the whole generalised “compressor surge oh no flutter noise when closing the valve” is generally more or less BS :) Little do they know when they buy a BOV and hear the flutter even louder potentially, because you are just allowing a more free release of air making it easier to hear in most cases, because reducing flutter is not the design purpose of a BOV
This is only half right. It puts pressure of the turbine face and force against the shaft back and forth. That’s what the common complaint issue is. Not that it stops the compressor from spinning or goes backwards. That came up randomly and got regurgitated ever since. And it’s more towards older turbos who already have wear and play. It makes the play and shaft wear/damage worse by adding unnecessary pressure. Also just because it’s no longer under load doesn’t mean it doesn’t still have a small amount of load on the turbo or still have force by spinning. I like the video, but this isn’t an end all just because some random kid on TH-cam “says so” lol
Of course, there is still a load while closed, but like you said, probably directed towards older turbos, any half decent non badly worn turbo won’t have the shaft effected by closed surge, I’ve never seen any example of that either to be fair and I’ve worked with turbos all my life, not on good working turbos anyway
Saabs, the pioneers to mainstream turbocharging, never used dump valves until 1985. And the compressor surging didnt do any harm to the earlier models.
I can imagine one reason being lower boost turbos of early times, closed surge would probably be more wearing on higher pressure systems but honestly, I think its a negligible difference, especially how everyone is always debating it and it’s so contradictory, like it’s never been such a significant different that people in general just haven’t come to a definitive answer.
Compressor surge is compressor surge. It doesn’t make it any less damaging that the throttle is open or not. It’s still trying to push air freely that it can’t. This causes faster bearing wear because the off centering torque and vibrations.
LOL. One is definitely more damaging than the other. Closed throttle is simply air between the turbo and throttlebody escaping back out the turbo. Open throttle compressor surge is doing the same thing, but while the throttle body is open. Meaning you're trying to force more air into an engine that can't make use of it, likely because the turbo size is mismatched. Open throttle compressor surge is definitely an issue.
@@strider5119 you’re saying “open throttle is an issue” like closed throttle is not an issue lmao. It has nothing to do with mismatched turbo size and everything to do with wastegate settings and control on open throttle while closed throttle has nothing to do with wastegates and everything to do with the use and settings of dump/ blow off valves. Remember, we’re talking about compressor surge here. The max turbo spool is controlled by the wastegate while the release of pressure after the compressor is released by a BOV, Recirc, Diverter or Dump Valve (different names and routing but solving the same issue) during throttle closure. What I believe you’re talking about and getting confused about is over boosting. Compressor surge is from the speed of the blades being too high for the amount of airflow at the time which in turn makes the blades lose “grip” on the air. This causes damaging vibrations and faster bearing wear by off centering… well, I already explained that.
@@fulano787 there is a difference. Open throttle the turbo is actively trying to make more boost. High boost pressure hitting high boost pressure trying to escape through the compressor puts massive strain on the thrust bearing. Closed throttle the turbo is idling, there is a pressure difference from the compressor that is lower than the pressure coming back at it.
@@fulano787 As long as you understand that during open throttle compressor surge, you are trying to stuff more air into the engine than it can take. That is bad compressor surge and is what damages the turbo. High boost trying to push against a wall. Closed throttle means the engine is no longer making boost, so the turbo is no longer pushing, the boost it was making can not be higher. This means that the air escaping is lower than what the turbo makes which is okay because turbos are designed to handle specific boost pressures. Normal boost pushing against vacuum.
There are some BOV with an internal max pressure bypass. Stock Subaru STI BOV does this, at least the older ones opens at about 23 psi. For those wishing to run higher boost on stock BPV, they modify this safety check and boost higher. Not sure how it helps with surge though,
so basically it will not damage your turbo but it will reduce performance since every time you slow down turbo on gear shift it will have to build up boost again when you open the throttle
@@DaytonaRoadster That's not the reason why... The length of the intake pipe is so absolutely negligible compared to the mass of air coming into that engine, not even superman would notice a difference between a BPV or BOV "response time" ... Two main reason that I can think of atm is that, most people who buy a new vehicle want it to be quiet. Believe it or not, not everyone with a turbocharged vehicle (there are TONS of them out there if you think about it ), wants to hear "PSSSSSHHHHHH!!!" every time they let off the gas. However, an even more important reason is this: If the vehicle has a MAF sensor setup (which most newer cars do), and you install a BOV, it's going to cause a huge unmetered air leak every time the valve is open, which can make the engine sputter, stall, throw a CEL, etc...
If you take ages to shift gear, maybe. Otherwise, no. The difference between bov and not having one is minimal. Flutter happens because there is compressed air between the turbo and throttlebody and it escapes. BOV's vent when the air between those same points reaches the amount its set to and will flutter for the rest anyway. You just don't really hear it at that point.
@@benjaminkrasznai2282 sorry, only just saw this. You just need to either block or delete your factory bov (or equivalent). Also blocking the vacuum line that goes to the bov. Sometimes you can get away with just blocking the vacuum line, but some bov's will still open with enough pressure. From turbo to filter, you want as much aluminium/stainless as possible, no plastic/factory stuff. You also want as free-flowing of a filter as you can get. Eg an aftermarket upgrade or just a pod filter. The sound will vary depending on the intake and also the volume of the intercooler/piping. Some cars sound shit when they flutter, some sound fantastic.
From an engineering perspective, 'off-boost' surge is still a problem. Categorized as partial flow reversal due to air stall, the sound that you hear are large vibrations being experienced at the compressor blades and subsequently high stresses. Over a certain period of time, these stresses (or stress cycles) can and will cause fatigue cracks to occur, and eventually either the blade tips or entire blades can become heavily damaged. Anyone who says that off-boost surge is fine is.. well, wrong. :)
Ahh praise be to this video. I shall share it far and wide so I don’t have a group of 17 year olds telling me my turbo is about to blow... (yes double entendres intended)
I like the flutter of the close throttle compressor surge rather than a blow off valve because the search goes STUTUTUTUTUTUTU while the blowoff valve just goes tshhhhhhh.
After about 20-30 minutes of google searching and a bit of independant thinking led me to the conclusion that this video is plain wrong. Turbo surge of any kind is bad for the bearings in the turbo. If you were coming off a 7k rpm pull, and lift the pedal all the way, the throttle plate closes, but the engine does not wind down in an instant, so the exhaust is still spinning the turbine and air returning from the throttle body is pushing against that spin, via the impeller, in the opposite direction. This opposing force creates a lateral load in the turbine-impeller shaft and hurts bearings. Why else would anyone making big power buy a BOV? just to waste money and add weight?
The reason google told you that is because forums are full of people spreading a myth they don't understand. They just read something and believe it. Plenty of people making HUGE power don't run BOV's. People used to always say "goldfish only have a 3 second memory" for decades, only to be told they're actually full of shit. I've seen plenty of pistons go through blocks, plenty of transmissions give out, but I have never seen someone need to replace a turbo due to running no bov.
@@strider5119 it’s the equivalent of a placebo fir example Europe cars are unreliable or parts are expensive when the counter is actually more expensive majority of the time
Surge is a limitation of any centrifugal compressor in that it can't raise the pressure without a minimum flow. When you put a big compressor on a small turbine that runs on a small engine it's likely to get surge when starting to make boost at low rpms
@@strider5119 Any centrifugal compressor has a surge line on the compressor map. That is an area of the map that shows the lower limit of air flow and higher limit of pressure at that low air flow. Any modern turbo engine doesn't get in that area of the map because the right turbo choice.
hx on my rb for years now no bov com surge can be elevated with either flat shift enabled on aftermarket eco and or supercharger bypass valve this also bypasses surge at wot :)
tubejorrit - Unless you have a open/atmospheric bov, it's not a great idea. Basically all turbo cars come with recirculating bov's from factory because they measure air through a MAF. If you change it to an open bov or block it off, you'll need a MAP based tune. COBB makes great devices for tuning Subarus
Do the bov mod and block the little pressure tube with a 6mm grub screw and then drill a 1.5 - 3mm hole in the tube after the screw. You now have a reference pressure of atmosphere for the bov spring instead of intercooler pressure. That gets you a bov that holds as much pressure as you want and causes a surge flutter before it then vents as normal. You do however loose the backup safety feature of the bov opening automatically at about 18psi boost pressure. You still need some form of venting on a subaru with a maf as it doesn't like air reversed back through the maf sensor. If you go vent to atmosphere all that will happen is that when you go off throttle it'll run rich for a second. That's it. You then need a speed density tune to fix that.
@@JolleBoiii No you don't. Recirculating bov's vent back before the turbo and that then goes to atmosphere via the filter. Vent to atmosphere bypasses the filter. Neither of them will do fucking anything to your cars tuning.
So how do you correct open throttle surge (ie turbo is too spooled for motor at a lower rpm)?? It's not to fix the turbo lol you definitely need a valve somewhere to correct it 🤔
So if it’s installed correctly, do you still need a blow off valve? Because if you have a blow off valve you won’t get the closed throttle flutter, correct?
Open throttle compressor surge happens when your turbos to big for your displacement. So the bigger the better doesnt really fit turbos. The airmass still needs to go through the engine. Should be fixable with programming but then you could just take a smaller turbo
Wait but I thought flutter is better the a bov bc it can retain some of the compressed air creating less turbo lag where as the bov removes all of the air leaving with more turbo lag.
No bov will slow the speed of the turbine between shifting. A bov will cause the turbo to spin higher rpm between shifts helping with lag but you wont really notice a difference enough to feel it imo
Wait.. so if it flutters straight after you take your foot off the accelerator it doesn’t harm your turbo? I’ve been searching for a video and this is the closest that’s made any sense
It will not damage the turbo but wear a little bit more over the years im sure. In the end the spool get opposite force, with blow off valve it will spinning only one way for it entire life.
Also not mentioned here: without a blow off valve, all that fluttering back pressure acts like a brake on the turbo wheel, slowing it WAY down any time you let off the throttle, like between shifts if you have a manual transmission, so your losing performance by having to re-spool the turbo every time you let off the throttle and get back on it. Also, without a blow off valve, every time you let off the throttle and get that sweet sweet fluttering sound, it's creating a MASSIVE boost spike for a second or so (much higher than your normal boost pressure) and that has been known to cause pipes and intercoolers to burst.
Not mentioned here because that doesn't happen, flutter does not slow the turbo down, High Performance Academy have a video tested exactly that and there is no difference in turbo speed after lifting off the throttle between running a valve and running no valve, they both go down at the same rate but anybody that has done it could tell you that, if it make any difference in turbo lag it would not be common place in motorsport, also if it makes a pipe or intercooler burst you must have the worst ebay special known to man, the spike in boost pressure is not that much that it would cause that unless you were already at the limit and by the limit I means running like 100+ psi on said ebay special.
Putting pressure while there’s still inertia spinning the wheel the opposite way will still have some effect on the bearings. How ever most big turbo manufacturing company’s beef up bearings and shaft cuz it needs to hold more boost in the first place. Ya closed shutter isn’t as bad but it’s still not necessarily healthy either. What I’m trying to get as is don’t go making that noise every time u put your foot on the petal and you’ll be fine. But if u do it 24/7 (no it will not break right away) but it can cause prematurely failures.
Is also wouldn’t work if u don’t have a 100% blow off valve. The ecu accounts for the air. You’ll basically loose power or fuck up ur tune. There’s a reason big trucks have 100% BOVs they want the turbo to last as long as the Diesel engine
@@eztrash4903 You wont lose power or fuck up a tune. The air shooting through a bov still comes out between the turbo and maf, so it'll either read the air twice or it won't. With or without a bov, it's the same air flowing.
So my 2014 Audi A4 2.0T Quattro does what sounds like an open throttle surge. I do have a cold air intake so it can be heard very clearly under heavy load. What do I have to do to fix this?
So the take-away from this video then, is that turbo flutter is ok, and doesn't hurt the lifespan or longevity of the turbo? Cuz if thats the case, I'm buying a BPV for my WRX haha
then how come I lost all my chu chu noises when upgrading to a larger turbo? recirculate blow off valve is also installed before and after the upgrade.
Finally someone who actually understands how this works. Thank you CT.
ali p how does he understand it? He just explained it’s ok. He showed no examples or reasoning as to why. Having 20+ years in machine and car shops and understanding tolerances and bearings back pressure under load or not is still pressure. Which is going to put force on the bearings which will wear one direction more than another. This wearing the bearings to premature failure.
The whole it wears under WOT but not when it’s no makes no sense. Either way it’s back pressure on the turbine and bearings. So either it does or doesn’t at all.
Manufacturers understand better. And they put valves to protect from surge. Thank you manufacturers.
Dan Slotea not true, they are mainly in place to prevent the noise and due to they fact that many standard hot wire/thin film air flow meters could not measure the direction of air flow, and as surge when surge occurred the air flow meter incorrectly measured more air than was being consumed by the engine, causing a temporarily rich tune and emissions problems.
The Anti surge was just a happy coincidence, many early turbo cars of the 80s had no bov.
@@renners9636 Many 80s cars also had Brown interiors, solid rear axles and were absolutely terrible. It doesn't make them correct.
Also that was like 37 years ago, technology changes.
Look at Borg Warner.
No Grip can you be more specific in your argument against me?
My statement was very simple and only covered one aspect, that the main reason cars were initially fitted with blow off valves was not to protect against *damage* from compressor surge itself but to stop incorrect fuel readings under surge conditions and to stop annoying noises that most drivers would not expect from a normal car.
I made absolutely no claim of anything being better, the implication of me mentioning some 80s gasoline cars not having blow off valves was to validate the 100s of thousands of turbochargers that have lived and live without being destroyed by compressor surge, I never advocated it as correct, but simply noted in the case of many oem cars that it is was a design that did not doom the turbocharger to early mechanical failure.
Manufacturers are more worried about possible emissions and noise issues than a few turbos failing sometime after warranty is up.
Maybe turbos running 30+psi are more susceptible to wear I couldn’t say.
So without a blow out valve, the car will laugh. With the blowout valve, the car will sneeze??
fuck this comment i love it
I like it when it laughs
I wil remember this comment for a long time
Hahaha dude
Yes.
Thank you so much for this, please do keep making these types of videos where you explain common misconceptions. Superb guys
Wow! So like half of us thought flutter was just a fancy sounding blow-off valve haha.
James Russo that’s what has made me so pissed! All these “tuner” 600whp subies talking bout “it’s a BOV”
maybe 10% its clearly not bov. BUT some of the turbo cars that makes flutter noises does have bov but it only realeases part of the boost so the sound is kinda mixed
some people wind there blow off valves up tightly so it surges on low boost and opens the blow off valve on high boost
Yep my car flutters when I roll off in normal driving and chirps when I'm getting into it. Just depend on much boost there is before lifting.
GlassTopRX7 how tight is your bov set?
Thanks! I was so worried with my quad turbo charged & dual supercharged Civic Si, with stock internals, would break all my turbos.
ErwinSchrodinger64
i wish this was trye and you had mad vids about it bruh
This is an automatic message to notify anyone that ErwinSchrodinger's quad turbo charged & dual supercharged Civic Si, with stock internals, had so much horsepower and so fast, it became a time machine and he went back in time.
ErwinSchrodinger64
all that was possible due not using bov
🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣
A civic can handle 1000 hp on stock internals easily, fax
Been running no BOV on my single turbo 1JZ for near on 3 years now. Makes 20+psi on e85 reliably all day every day without issue. Why fix something if it isn't broken?!
You'll be fixing it a lot sooner than someone with a BOV.
Archer
old turbo buicks with blow thru system didnt have bovs and you can still find perfectly working ones with the same old turbo.
so after 25+ years and thousands of miles and still no broken turbo...
Also to note, WRC cars don't use BOVs either because (believe it or not) they slow the impeller speed down more than without one causing more lag ;)
as far as i know the bmw m6 GT3 don´t use a bov either and you can hear the flutter when they let off the gas ^^
andrenegwer says the guy parroting what he saw in a video from a very respectable, but less experienced member of the community. They are much more experienced experts who will tell you the opposite. What he covers is is mostly true but you still cause premature wear without a valve regardless.
I actually like the flutter sound much more than the blow off one. It just sounds more epic :)
I get the best of both worlds with the Tial Q on my ms3. Spring in it is a -12 psi spring, and the vacuum in the intake manifold takes about a quarter to a half second to go from positive boost to -12 vacuum, and therefore it takes that long before the valve opens after boost. I get this lovely "stutu-schhhhh" noise from it and I absolutely cannot wait until I have a Garrett GTX2867R gen II on it and can hear the noise a 9 blade compressor makes vs the k04 6 blade.
Thanks for making this video because people that never owned a turbo car comment and try to act li,e they know their shit.
my first turbo car was a -99 saab 93 2.0t and i tuned it from 150 to 270 without a bov, and its still fine and it has 320000 km on the clock!
@@garren3498 hows ur saab holding lol
Hands down the clearest explanation for this. Thanks guys.
If you're running the correct sized turbo, intercooler and piping for your setup, a BoV isn't necessary, the only thing a BoV MIGHT, and I stress the might, help with is eliminating lag (if you even have any) between gear changes as the turbine of the turbo won't slow down as much with the surge of pressure when the throttle blade is closed. As for the increased wear on the turbo when not using a BoV, for every study I've seen saying that it wears the turbo quicker, there's another that says it won't! :/ From my own experience, the only benefit I've noticed from a BoV has been reducing lag between gear changes. I put something like 15000 miles on a mk3 Supra 2.8 single turbo I built back in 1999 without a BoV then after some advice from a mk4 Supra owner, I fitted a BoV and it did help to eliminate the lag I was getting between gear changes. I ran the car for 2 years after that (must've been at least another 20000 miles) without any noticable signs of wear on the turbo, I sold the car to a friend who ran it just over a year before smashing it and one of the few things that was ok to salvage was the turbo!
Yeah, hear changes and when you close the throttle before reopening, I have noticed slight differences in lag reduction with a well placed BOV, as for longevity... I don’t think it’s that dramatic of a difference with our without as long as your system in balanced like you said
yes
good fix for this is flat foot shifting 😂
I'm under the impression you're mistaking the purpose of a blowoff valve and a wastegate. The boost control solenoid in conjunction with the wastegate and recirculation valve is what should maintain boost pressure between shifts, a blow off valve in theory is only there to blow off air pressure when you come off throttle
@@theposerhoser No he's correct. A wastegate is only there to prevent overspeeding of the turbo. A recirculation valve has a very similar job as a bov, a bov vents to atmosphere and a recirculation valve vents back to the inlet of the turbo. Not sure why you added the wastegate to the mix.
Car Throttle THANK YOU!! At fucking last somebody got it right!!
Seriously: Utmost respect to you for actually RESEARCHING this subject and not just repeating what every forum / back of BOV box said.
Wait so thath means we can have sututututu ?
Stoteliu Siaubas that’s what I’m hearing.. throwing out BOV now..
BRAABABABA STUTUTUTUTU
Been saying this for years and no one would believe me
only low boost
@@randiey95 define low boost because im thinking if 15 psi qualifies🤔
That R33 at the end was purely demonic
agreed
UK:CarThrottle = USA: DonutMedia
Bitvh who do you love?
Who you calling a bitch?! bitch
LMFAO the yg reference is great
Both
of course there's a VL commodore...
why wouldn't there be?
aka. Dose Mobile :D
Up the Vl and Rb30.
haha love my vl and I was surprised it made it into what I assume is an american made video but almost all turbo vls are bound to be flutter machines. Mines soon to join the turbo charged crew ;)
VL most over rated car in Australia pisses me off but I love the rb but just so over rated compared to batta
As a Machinist/Welder/Fabricator/Mechanical Engineer, in 2004 or there about's, I got to work on a diesel semi-tractor that was attempting a Bonneville world speed record for that class. The diesel engine was turbocharged and producing 75+ psi. The turbo stall was discovered with a high-speed camera aimed at the fan. This wheel was coming to near complete stop and re-spooling. The solution was to add a Roots Blower to the mix to positively insure that the flow from the turbo was moving forward. This semi was geared so tall that it needed another tractor to push it to 75 mph just to get going in first gear.
Well, this is the coolest thing I've read all day. Funny enough a day that someone was trying to tell me how bad compressor surge is, which is why TH-cam suggested this video to me.
Do you happen to remember who or what company that was? It wasn't Cat with the race C10, was it?
@@wallcouldtalk Search TH-cam for "Ye Old Dragon".
How was the turbo coming to a near complete stop?
Got a link to a video of that? cause it sounds bullshit to me. Turbos spins at tens of thousands of rpms, it's not going to stall and come anywhere near a complete stop in between gears. That's an outrageous claim
it's obvious that anyone who says that hasn't driven or even heard a turbo car IRL.. good vid man.
Had my own turbo spin the nut off the compressor due to closed throttle surge and seen others do it too. It is all good if your turbo runs a left hand threaded shaft but the ones i have seen undo are right hand threaded. The turbines inertia due to weight is greater than the compressor wheel so it tends to back off the nut on the compressor wheel when there is a differential of forces applied. Cheers.
knock off garrett and BW moment
Got proof that it was specifically compressor surge that caused that? Cause I have never heard of that happening, ever lol
Could you do a video about blower idle surge? I never fully understood the concept behind it. Thanks!
same concept. to much air is being pumpd, vs what is being used.
Already knew, but it's nice to see someone else who doesn't believe the forum ninjas. For everyone who isn't sure ; Blow off and recirc valves only help stop compressor stall on over run/closed throttle. Usually vacuum operated, though I did see a rather complex electric set up that was supposed to keep it spooling longer. The best way to do that is antilag, but that's the easiest way to shorten the life of any turbo, but so much fun.
Pushing 24psi no bov/dv for atleast 6 months daily driven. No issues yet. It makes sense that the free spinning turbo can chop the air with reverse pressure with minimal wear to the bearings/shaft because of its free spinning state.( whatever exhaust flow from the engine while shifting wouldnt be nearly the pressure returning through the intercooler) I don’t understand why so many others preach its pre detonation of the turbo?
You’ve just convinced me to put a cover plate on my blow off valve. Congrats.
I've had a ghetto blanking plate on my WRX Wagon's stock recirculation valve for over 5 years and 40,000 miles with no issues. If you want flutter then I highly recommend it. Every genuine expert I've spoken to had said it's not going to cause any harm. Especially in a stock turbo that doesn't run particularity high boost. 👍
I think it depends on the tuning set up if a blow off valve is necessary.
In my car i had the recirculation factory valve . It makes a chousss sound.
Lately there's a problem that causes loss of boost and i have to go to my mechanic to solve it.
By the way what is ghetto blanking plate?
I had seen some comments about that and I never did understand how it could spin the compressor backwards, turbochargers are essentially non-postive displacement pumps and a fluid pushed backwards through one would be extremely inefficient at causing any movement of the compressor wheel.
Its scary to me that people don't actually get this as it's the most BASIC understanding of how a turbo works. Think about that for a while. these are the same people that yell ''RICER'' if you made a modification they don't approve of.
StreatBeatsAudio Subwoofers basically people who call themselves car guys but have no clue at all
It sounds to me like you're just band-wagoning, because you aren't really providing reasoning behind your argument. You're simply persecuting. Compressor surge fundamentals are not the most basic understanding of how a turbo works. That's usually stage 2 or stage 3 in understanding a turbine's mechanics. An inexperienced person who has just finished their build wouldn't likely be aware that their blow-off valve serves purpose outside of alleviating pressure in charge pipes and intercooler piping/intercooler. If they heard open throttle compressor surge for the first time, they might just assume it's cool turbo noises and functioning as normal. Once they've blown the seals and bearings out of the turbo, then it might be something they learn. Also, some of your statements don't even correlate. You're a bit all over the place, which is what leads me to the conclusion that you're simply here to make others feel bad to make yourself feel better about your own ignorance. I'm not attacking you, but I would ask that you not attack others. If you think you have such a complete grasp on turbo-charging, perhaps you should do some research into intake harmonics and then come back and comment. You still have a lot to learn as well. Everyone starts somewhere. Learning is a process. I've spent years of my life building turbo'd cars and still learn things every day through trial and error, other people providing me information and tips, and research and equations. If you assume compressor surge is a fundamental pillar in understanding turbo-chargers, you've never seen a 16 year old driving a boosted Civic with no blow-off valve, no intercooler, no waste-gate, and no BCM or piggy-back. Turbo-charging is more complex than you are for probably prepared.
@@bestleesinna7702 lol
@@bestleesinna7702 turbo flutter does not wear the turbo out due to simple fluid dynamic laws
@@the_modfied_car4903 do you understand how bearings, friction, impact and directional force work? Cause what you said makes me think you don't. Turbo flutter is puts force on the fins in one direction, abruptly ceases that energy, which causes secondary forces to commence. This is a back and forth motion that wears down bearings and shafts. A smoother change in pressure results in less violent motion and reduced wear. You don't know what you're talking about. Fluid dynamics are all fine and dandy in theory but mechanical elements are your point of wear. Anything that moves, wears. You combine the immense heat and rpm a turbo operates at and you get accelerated wear. Not to mention the difference between double-sleeve, sleeve-bearing, and dual-ball-bearing turbos. Turbo flutter causes wear. Arguing against that isn't ignorance now, because you should know better. Arguing against it is stupidity because you're arguing against physics. This kind of wear is demonstrated by the price-hike of dual-ball-bearing turbos despite them being cheaper to manufacture than other varieties. It's because those forces don't wear them AS much, but still do. I just...I can't even talk to you right now. If you don't know something, ask. But don't try to teach people incorrectly.
thanks CT that cleared my confusion. Now I can have highest settings during acceleration with no flutter , but only after you lift the throttle-closed.
I could be wrong but having a bov does make for much quicker boost response if you are going to be on and off the throttle frequently as in road racing,time attack,off road rallying and auto cross.
Yessss finally. I argued with people all the time about this, glad someone finally makes a detailed video explaining the differences.
Thank goodness I had this saved cuz my dad did t believe me when I told him it wasn't bad to not have a blow off valve. This video amongst much more research finally proved to him it wasn't bad for my car which I bought myself that he has never and will never need to put money into
As a father, I will act like that, because it makes my kids want to prove me wrong. It's a kind of test to see what lengths they will go to prove what you think is real. Also you learn more from doing so rather than not having to. Have fun out there in your turbo rig. 🤙
Turbos are great.
I have a book by career long mechanics that I explained before that goes over this and you do cause premature fatigue failure on turbos and increase turbo lag without a compressor bypass/blow-off valve. With the valve you prevent pressure waves going back into the impeller and the impeller is kept spinning without interruption reducing lag. I’d rather not put any stress on my expensive parts than do so just to hear “wooooooosh Stu-Stu-Stu-Stu-Stu”
Did you watch the video?
idiots just put in their own two sense weather its wrong or right
*cents *whether , unless your comment was a joke. Lol
Honestly, thank you so much CarThrottle.
This finally answerd my questions. Thanks guys. Subscribed.
Does it means if no blow off valve in the system there will be more turbo lag because the turbine had slowed down so much when throttle valve closed?
Anas Takiyudin it's really not that bad at all
I'd say it depends. If you're letting off the throttle for a brief moment (like changing gear) residual pressure that haven't gotten out through the turbo yet will help to build the target pressure faster, but if you let off and leave it for a longer time (so the pressure can completely escape), then yes, rotor will take more time to spool up. Nevertheless, in both cases, the differences are barely noticeable.
Surge is better for response as the intercooler still has a charge in it that it otherwise has not dumped all out through a bov.
Lag is actually the time it takes for the pressurised air from the turbo to make it to the manifold. A top mount will have less lag than a front mount typically.
Ok, the hot side is the turbine, the cold side is the compressor. They spin at the same time being linked with a solid shaft. Ok moving on, what you're probably trying to describe is boost threshold where there is enough exhaust gas to spin the turbo to the point it produces positive pressure. Turbo lag as I said above is what happens above that boost threshold.
The first problem I see with this video is while yes, you're right in your explanation dispelling this myth - but "Oh you're wrong because 'Car Throttle Extra' said so" is most likely not going to cut it.
Maybe you could cite your sources behind the logic explained in this video?
There can be surge with wide open throttle as well.... If you mismatch the compressor wheel with the engine flow demand. Its not the air that is trapped. Its the compressors wing stall that makes the fluttering noise. You can also have surge in airplane engines as well and it vibrates in similar fashion.
Never had a turbo issue due to closed throttle surge, both cars for over 5 years now. Good video, easy enough for all keyboard warriors to hopefully understand...
Heads up for those that run a Maf sensor on the turbo inlet, subaru guys I'm talking to you. Doing this mod will cause problems with your tune. The air moving out of the turbos inlet on closed throttle is being metered and telling the computer it needs more fuel to go into the cylinders on closed throttle.
Ran no BOV on 240sx KA-T
it felt like a better turbo response not to have a BOV, because when I'm off throttle the would turbo flutter for around 2 second. So I guess for those 2 sec, it's like I have reservoir of boost ready to use. So If I opened the throttle within 2 seconds after closing the throttle the boost would just shoot back up to the boost limit almost instantly.
Great video thanks ... might be worth doing one to explain why BOVs are pointless on turbo diesels ;-)
Well going on my car engine - it has no throttle plate. and is a deisel turbo, still get some nice flutters though when off thy gas!
BRB going to install a heavy ass spring on my N54 Blow-off Valve because I love that flutter sound.
What bov you using on your n54?
It can’t surge if it has no load
No load no surge
Just pretty pretty noises
Tbh the only advantage a BOV is in a manual car so the turbo doesn’t slow between shifts.
The only thing a bov does is stop back flow when throttle is closed. To keep the turbo spinning in between shifts you need a recirculating valve that reintroduces the air into the turbo intake
Thanks for addressing facts, there is so much misinformation online it’s unreal, magazines still publish about compressor surge to try and sell turbo smart BOV’s lol, fair enough that if you have higher boost and too much trapped air then extra resistance against the impeller over a longer time frame may not be the best thing, but the whole generalised “compressor surge oh no flutter noise when closing the valve” is generally more or less BS :)
Little do they know when they buy a BOV and hear the flutter even louder potentially, because you are just allowing a more free release of air making it easier to hear in most cases, because reducing flutter is not the design purpose of a BOV
Learn something new everyday when you’re willing
Thanks for this now I can run no bov on my new project
Ive been running my Big turbo A4 for a few years without a BOV. zero shaft play.
2:37 the subtitles say "Music" when there is the BOV sound 😂
Guten Tschüss my favorite genre of music😂😂
They are not wrong
This is only half right. It puts pressure of the turbine face and force against the shaft back and forth.
That’s what the common complaint issue is. Not that it stops the compressor from spinning or goes backwards. That came up randomly and got regurgitated ever since.
And it’s more towards older turbos who already have wear and play. It makes the play and shaft wear/damage worse by adding unnecessary pressure.
Also just because it’s no longer under load doesn’t mean it doesn’t still have a small amount of load on the turbo or still have force by spinning.
I like the video, but this isn’t an end all just because some random kid on TH-cam “says so” lol
Of course, there is still a load while closed, but like you said, probably directed towards older turbos, any half decent non badly worn turbo won’t have the shaft effected by closed surge, I’ve never seen any example of that either to be fair and I’ve worked with turbos all my life, not on good working turbos anyway
Saabs, the pioneers to mainstream turbocharging, never used dump valves until 1985. And the compressor surging didnt do any harm to the earlier models.
I can imagine one reason being lower boost turbos of early times, closed surge would probably be more wearing on higher pressure systems but honestly, I think its a negligible difference, especially how everyone is always debating it and it’s so contradictory, like it’s never been such a significant different that people in general just haven’t come to a definitive answer.
Didnt know u could get compressor surge on a centif blower. 😮
Compressor surge is compressor surge. It doesn’t make it any less damaging that the throttle is open or not. It’s still trying to push air freely that it can’t. This causes faster bearing wear because the off centering torque and vibrations.
LOL. One is definitely more damaging than the other. Closed throttle is simply air between the turbo and throttlebody escaping back out the turbo. Open throttle compressor surge is doing the same thing, but while the throttle body is open. Meaning you're trying to force more air into an engine that can't make use of it, likely because the turbo size is mismatched. Open throttle compressor surge is definitely an issue.
@@strider5119 you’re saying “open throttle is an issue” like closed throttle is not an issue lmao. It has nothing to do with mismatched turbo size and everything to do with wastegate settings and control on open throttle while closed throttle has nothing to do with wastegates and everything to do with the use and settings of dump/ blow off valves. Remember, we’re talking about compressor surge here. The max turbo spool is controlled by the wastegate while the release of pressure after the compressor is released by a BOV, Recirc, Diverter or Dump Valve (different names and routing but solving the same issue) during throttle closure. What I believe you’re talking about and getting confused about is over boosting. Compressor surge is from the speed of the blades being too high for the amount of airflow at the time which in turn makes the blades lose “grip” on the air. This causes damaging vibrations and faster bearing wear by off centering… well, I already explained that.
@@fulano787 there is a difference. Open throttle the turbo is actively trying to make more boost. High boost pressure hitting high boost pressure trying to escape through the compressor puts massive strain on the thrust bearing. Closed throttle the turbo is idling, there is a pressure difference from the compressor that is lower than the pressure coming back at it.
@@Mr.Wongburger yes, compressor surge is different. No, it does not happen at idle.
@@fulano787 As long as you understand that during open throttle compressor surge, you are trying to stuff more air into the engine than it can take. That is bad compressor surge and is what damages the turbo. High boost trying to push against a wall.
Closed throttle means the engine is no longer making boost, so the turbo is no longer pushing, the boost it was making can not be higher. This means that the air escaping is lower than what the turbo makes which is okay because turbos are designed to handle specific boost pressures. Normal boost pushing against vacuum.
There are some BOV with an internal max pressure bypass. Stock Subaru STI BOV does this, at least the older ones opens at about 23 psi. For those wishing to run higher boost on stock BPV, they modify this safety check and boost higher. Not sure how it helps with surge though,
so basically it will not damage your turbo but it will reduce performance since every time you slow down turbo on gear shift it will have to build up boost again when you open the throttle
thats why WRX recycle the air, so they dont have to wait again
@@DaytonaRoadster That's not the reason why... The length of the intake pipe is so absolutely negligible compared to the mass of air coming into that engine, not even superman would notice a difference between a BPV or BOV "response time" ...
Two main reason that I can think of atm is that, most people who buy a new vehicle want it to be quiet. Believe it or not, not everyone with a turbocharged vehicle (there are TONS of them out there if you think about it ), wants to hear "PSSSSSHHHHHH!!!" every time they let off the gas.
However, an even more important reason is this: If the vehicle has a MAF sensor setup (which most newer cars do), and you install a BOV, it's going to cause a huge unmetered air leak every time the valve is open, which can make the engine sputter, stall, throw a CEL, etc...
If you take ages to shift gear, maybe. Otherwise, no. The difference between bov and not having one is minimal. Flutter happens because there is compressed air between the turbo and throttlebody and it escapes. BOV's vent when the air between those same points reaches the amount its set to and will flutter for the rest anyway. You just don't really hear it at that point.
Great explanation. So now if I take off my stock bov on my stock 1.4 tsi I will not have any problems? I love the stututu sound
A blow of valve will work at WOT they open at whatever PSI they are calibrated for regardless of throttle position
A guide how to produce that sound from your turbo would be the best !
I could explain it to you, it's very easy
@@strider5119 can you explain it to me? Would be helpful!!
@@benjaminkrasznai2282 sorry, only just saw this. You just need to either block or delete your factory bov (or equivalent). Also blocking the vacuum line that goes to the bov. Sometimes you can get away with just blocking the vacuum line, but some bov's will still open with enough pressure. From turbo to filter, you want as much aluminium/stainless as possible, no plastic/factory stuff. You also want as free-flowing of a filter as you can get. Eg an aftermarket upgrade or just a pod filter. The sound will vary depending on the intake and also the volume of the intercooler/piping. Some cars sound shit when they flutter, some sound fantastic.
From an engineering perspective, 'off-boost' surge is still a problem. Categorized as partial flow reversal due to air stall, the sound that you hear are large vibrations being experienced at the compressor blades and subsequently high stresses. Over a certain period of time, these stresses (or stress cycles) can and will cause fatigue cracks to occur, and eventually either the blade tips or entire blades can become heavily damaged. Anyone who says that off-boost surge is fine is.. well, wrong. :)
You're wrong
@@BAYAREAMX well I'm not, but believe whatever makes you happy!
Agree!!
Yeah but it sounds really good...
No im not 12
(Edit: changed profile pic)
Gordon I'm 13
Did you actually watch the video
Yet you have a GTR badge as your profile picture as do a lot of 12 year olds.
SSSSSSSUTUTUTUTU
Looks really shady with that gtr logo lol
It is too good. Very simply explained.
Ahh praise be to this video. I shall share it far and wide so I don’t have a group of 17 year olds telling me my turbo is about to blow... (yes double entendres intended)
Thank you! So my Cooper S Turbo Flutter video can stop getting hate comments haha! Thanks CT!
HaphazardGarage "Click Bait Level 300!!!
Ashkar 300 ain’t bad!
HaphazardGarage Nop "1000!"
I like the flutter of the close throttle compressor surge rather than a blow off valve because the search goes STUTUTUTUTUTUTU while the blowoff valve just goes tshhhhhhh.
thank you so much, now my question is, does the bigger the turbo mean more flutter or does it matter?
So i can keep that stu stu stu that puts that smile on my face☺️ yay!!!
After about 20-30 minutes of google searching and a bit of independant thinking led me to the conclusion that this video is plain wrong. Turbo surge of any kind is bad for the bearings in the turbo. If you were coming off a 7k rpm pull, and lift the pedal all the way, the throttle plate closes, but the engine does not wind down in an instant, so the exhaust is still spinning the turbine and air returning from the throttle body is pushing against that spin, via the impeller, in the opposite direction. This opposing force creates a lateral load in the turbine-impeller shaft and hurts bearings. Why else would anyone making big power buy a BOV? just to waste money and add weight?
20-30 minutes of google searching is better then people with 20+ years of experience not running blow off valves.
The reason google told you that is because forums are full of people spreading a myth they don't understand. They just read something and believe it. Plenty of people making HUGE power don't run BOV's. People used to always say "goldfish only have a 3 second memory" for decades, only to be told they're actually full of shit. I've seen plenty of pistons go through blocks, plenty of transmissions give out, but I have never seen someone need to replace a turbo due to running no bov.
Then why do companies like Canam who make turbo engines for side by sides not run a BOV at all or high revving high performance engines?
@@strider5119 it’s the equivalent of a placebo fir example Europe cars are unreliable or parts are expensive when the counter is actually more expensive majority of the time
Surge is a limitation of any centrifugal compressor in that it can't raise the pressure without a minimum flow. When you put a big compressor on a small turbine that runs on a small engine it's likely to get surge when starting to make boost at low rpms
Old comment, but that's open throttle compressor surge.
@@strider5119 Any centrifugal compressor has a surge line on the compressor map. That is an area of the map that shows the lower limit of air flow and higher limit of pressure at that low air flow. Any modern turbo engine doesn't get in that area of the map because the right turbo choice.
hx on my rb for years now no bov com surge can be elevated with either flat shift enabled on aftermarket eco and or supercharger bypass valve this also bypasses surge at wot :)
Time to block my blov of my Subaru :)
tubejorrit - Unless you have a open/atmospheric bov, it's not a great idea. Basically all turbo cars come with recirculating bov's from factory because they measure air through a MAF. If you change it to an open bov or block it off, you'll need a MAP based tune. COBB makes great devices for tuning Subarus
Do the bov mod and block the little pressure tube with a 6mm grub screw and then drill a 1.5 - 3mm hole in the tube after the screw. You now have a reference pressure of atmosphere for the bov spring instead of intercooler pressure. That gets you a bov that holds as much pressure as you want and causes a surge flutter before it then vents as normal. You do however loose the backup safety feature of the bov opening automatically at about 18psi boost pressure.
You still need some form of venting on a subaru with a maf as it doesn't like air reversed back through the maf sensor.
If you go vent to atmosphere all that will happen is that when you go off throttle it'll run rich for a second. That's it. You then need a speed density tune to fix that.
hope your on a speed density tune
MV60 is right
@@JolleBoiii No you don't. Recirculating bov's vent back before the turbo and that then goes to atmosphere via the filter. Vent to atmosphere bypasses the filter. Neither of them will do fucking anything to your cars tuning.
Just blew both turbos after 6k miles over 4 years...No BOV. Got turbos repaired and now running a BOV. Ball bearing garret turbos on a 997 Turbo.
Your turbos didn't die because you weren't running a blow off valve.
So how do you correct open throttle surge (ie turbo is too spooled for motor at a lower rpm)?? It's not to fix the turbo lol you definitely need a valve somewhere to correct it 🤔
Thanks for clarifying 😊
the first clip is in lebanon the village is called taybe i am from there
Thank you for explaining this great video
Thank you. I’ve been saying this for years
My GTI with K04 started to make this close throttle flutter after stage 1 (300hp 440Nm) , first thought that it's DV, changed but still same sound..
About time people learn..
Them supra’s sounds great, green one doing fly buy
And the 33 at the end
Because Bovs are illegal in Australia (mostly) it is unnecessary to run one and the turbo flutter does not mean the turbo is being damaged
Atmospheric venting bov's are illegal in Australia. You can have them if they're plumbed in.
so the surge actually (very slightly) lenghtens the lifespan of the turbo by slowing the turbine down?
That last one sounded siiiick
Thnx for the clarity, but what about diesels w/o a throttlebody?
So if it’s installed correctly, do you still need a blow off valve? Because if you have a blow off valve you won’t get the closed throttle flutter, correct?
Open throttle compressor surge happens when your turbos to big for your displacement. So the bigger the better doesnt really fit turbos. The airmass still needs to go through the engine. Should be fixable with programming but then you could just take a smaller turbo
I only learn from cartoon example, great video!
Is deleting my Electronic bov will b a problem? Audi a3 tfsi 1.8
So the flutter isn’t bad for the turbo as long as it only happens off throttle??
The car at the end scared the shit outta me XD
Thanks for clearing that up
Wait but I thought flutter is better the a bov bc it can retain some of the compressed air creating less turbo lag where as the bov removes all of the air leaving with more turbo lag.
No bov will slow the speed of the turbine between shifting. A bov will cause the turbo to spin higher rpm between shifts helping with lag but you wont really notice a difference enough to feel it imo
yeah the vl, great video, and also like all the other educational videos, keep it up👌
Wait.. so if it flutters straight after you take your foot off the accelerator it doesn’t harm your turbo? I’ve been searching for a video and this is the closest that’s made any sense
It will not damage the turbo but wear a little bit more over the years im sure. In the end the spool get opposite force, with blow off valve it will spinning only one way for it entire life.
Also not mentioned here: without a blow off valve, all that fluttering back pressure acts like a brake on the turbo wheel, slowing it WAY down any time you let off the throttle, like between shifts if you have a manual transmission, so your losing performance by having to re-spool the turbo every time you let off the throttle and get back on it. Also, without a blow off valve, every time you let off the throttle and get that sweet sweet fluttering sound, it's creating a MASSIVE boost spike for a second or so (much higher than your normal boost pressure) and that has been known to cause pipes and intercoolers to burst.
Not mentioned here because that doesn't happen, flutter does not slow the turbo down, High Performance Academy have a video tested exactly that and there is no difference in turbo speed after lifting off the throttle between running a valve and running no valve, they both go down at the same rate but anybody that has done it could tell you that, if it make any difference in turbo lag it would not be common place in motorsport, also if it makes a pipe or intercooler burst you must have the worst ebay special known to man, the spike in boost pressure is not that much that it would cause that unless you were already at the limit and by the limit I means running like 100+ psi on said ebay special.
Putting pressure while there’s still inertia spinning the wheel the opposite way will still have some effect on the bearings. How ever most big turbo manufacturing company’s beef up bearings and shaft cuz it needs to hold more boost in the first place. Ya closed shutter isn’t as bad but it’s still not necessarily healthy either. What I’m trying to get as is don’t go making that noise every time u put your foot on the petal and you’ll be fine. But if u do it 24/7 (no it will not break right away) but it can cause prematurely failures.
Is also wouldn’t work if u don’t have a 100% blow off valve. The ecu accounts for the air. You’ll basically loose power or fuck up ur tune. There’s a reason big trucks have 100% BOVs they want the turbo to last as long as the Diesel engine
@@eztrash4903 You wont lose power or fuck up a tune. The air shooting through a bov still comes out between the turbo and maf, so it'll either read the air twice or it won't. With or without a bov, it's the same air flowing.
That last surge tho :o
So my 2014 Audi A4 2.0T Quattro does what sounds like an open throttle surge. I do have a cold air intake so it can be heard very clearly under heavy load. What do I have to do to fix this?
2:08 I see what you did there.... Blowing off the steam....
So the take-away from this video then, is that turbo flutter is ok, and doesn't hurt the lifespan or longevity of the turbo? Cuz if thats the case, I'm buying a BPV for my WRX haha
EGC_Warlock im also looking for that answer
then how come I lost all my chu chu noises when upgrading to a larger turbo? recirculate blow off valve is also installed before and after the upgrade.